Telephone system.



F. M. SLOUGH.

TELEPHONE SYSTEM.

APPLICATION man IULY 15. ms.

Patented Mar. 25,1919.

2 SHEETS-SHEET I.

Jfizrsnfar Fran/11M F. M. SLOUGH.

TELEPHONE SYSTEM.

APPLICATION FILED JULY 15. I915.

Patented Mar. 25, 1919.

2 SHEETS-SHEET 2.

JUL/E2770!" ME eras earn -rrron FRANK M. SLOUGH, OF ELYRIA. OHIO, AS$IGNOR, BY MESNE ASSIGNMENTS, TO STROMBERG-CARLSON TELEPHONE MFG. G O., OF ROCHESTER, NEW YORK, A

CORPORATION OF NEW YORK.

'rnnnrionn'srsrniu.

7' Specification of Letters .Patent. patgnted 131 25, 1919.

Application filed July 15, 1915. Seria11\To.39,941.

To'aZZ whom it may concern: I

Be it known that I, FRANK M. SLoUGH, a citizen of the United States, residing at Elyria, in the county-of Lorain and State of Ohio, have invented certain new and useful Improvements in Telephone Systems; and I do hereby declare the following to be .a full, clear, and exact description of the invention, such as will enable others skilled in the, art to'which it appertains to make and use the same. 4 e

My invention relates to telephone systems and to improvements therein for the purposes ofperforming certain useful functions and attaining useful objects which will be apparent from a description of embodiments of the invention, and some of which will be mentioned in the following description of the two embodiments shown in the drawings.

Figure 1 shows diagrammatically a telephone system embodying my invention.

Fig. 2 is a modification of the embodiment shown in Fig. 1.

Referring first to Fig. 1 of the drawing at I and III are shown telephone lines, the line I leading from a substation shown at A to a main station shown at II, and the line III leading from a plurality of substations, one of which is illustrated at B to the main station II. Means are provided at the main station for connecting telephone lines together, here shown as a cord circuit C. I also illustrate at C a portion of a second cord circuit, since a portion is 'suflicient to explain this embodiment of my invention. Switching means are provided for connecting the link conductors at C to the telephone lines, which are here shown as plugs and jacks. The line I, which hereinafter may be called the calling line, terminates at the main station II in a plurality of jacks, two of which are here illustrated at J and j, and the line III, likewise terminates in a plurality of jacks, two of which are shown at J and j. The link conductors at C terminate in the plugs P and P, which are provided with contacts adapted to register with the contacts of the jacks when the plugs are inserted into the jacks to complete the connection. The cord circuit C is provided with plugs, one of which is shown at p.

Means are provided for apprising the opscribers.

erator at the main station that the subscribers upon the lines desire attention. The

callin-g lineis provided with a line relay S anda plurality of line lamps, one associated with each jack, the lamp X being associated with the-jack J and the lamp to being associated with the jack The line III, which may hereinafter be spoken of as the called line is likewise provided with a plurality of line lamps, the lamp X being associated with the jack J and the lamp :0 being associated with the jack j. The main station operator 1s provided with an operators set F which is adapted to be connected to the vlink conductors to furnish the operator with the means of communicating with the sub- \Vhen the operator observes the operation of one of the line lamps, the

switching means D is operated-in the form shown, by inserting the plug I, which will hereinafter be spoken of as the answering plug, into one of the line jacks, in case the cord C is used, say the jack J. The operation of the switch D will cause the actuation of both the relays N and L and when a subscriber is upon the calling line, the relay M willalso be actuated. The actuation of th'e relay L will cause the actuation of the relay T and the operators set F will be automat cally connected to the cord, so that the operator can communicate with the subscriber and learn h1s desire. "ofthe relay N cuts off the relay S and the The actuation line lamps from the line. The operation of gthe relay M opens the circuit of the relay K and completes a substitute circuit for the relays N and L through the conductor 3.

Assuming that it is the subscriber at B that is desired, and that the called line is idle, the operator actuates the switching means E by inserting the plug P, hereinafter spoken of as the calling plug, into the jack J, connecting the-calling and called line together through the cord circuit. The

actuation of the switching means E causes the operation of the relays N and L. The operator now places ringing current upon the called line by actuating one of the ringin-gqkeys, 1 shown in the upper right-hand corner of Fig. 1, say the key I, which causes the actuation of the master key I. This completes a circuit through the ringing relay Q, which connects the ringing generator tion shown in the drawing.

the connections.

U through the commutator H and the relay R to the called line. The subscriber will be automatically rung, and when response is made the relay R will be actuated, interrupting the circuit of the relay Q, whereupon the ringing is discontinued and the talking strands of the cord completed. The relay M will also be actuated when the subscriber responds.

Upon the termination of the conversation, the circuits of the relays M and M will be broken, restoring their contacts to the posi- This will interrupt the circuits of the relays N and L, so that the line relay S and the line lamps will be placed in condition to be actuated by the subscriber at A, should a recall be desired. Assuming that the subscriber at A does desire a recall and again operates the line lamps, such call may be answered by any operator in the exchange, whose position is equipped with a line lamp of the line I. Assuming the operator controlling the cord circuit 0 answers the call by inserting the plug 2 into the jack j, current will be placed upon the contacts 4:, 4 and the conductor 5, as soon as the contact 6 of the plug 19 engages the contact 4. This will cause the energization of the relays N and K, the relay N again disconnecting the line relay S and the line lamps of the line I and the relay K operatively disconnecting the line and cord by interrupting the talking strands of the cord circuit C without disturbing the switch D. The lamp W will also be flashed through the operation of the device Gr, indicating to the operator controlling the cord C that another operator has answered the recall of the subscriber A. Should the operator controlling the cord C desire to answer the call herself, she opcrates the key 0, which will cause the actuation of the relays N and T, placing herself in position to answer the call herself. When the plugs are withdrawn from the jacks, of course, the system is restored to normal.

It will be seen that one of thQ'PIiIlClPfil objects of my invention is to release the telephone line immediately the conversation is terminated, so that the subscriber thereon can immediately secure a recall, thereby taking advantage of the interval of time which always exists between the termination of one conversation and the taking down of This interval is sometimes very long when the operator is busy and does not have time to take down such' connections as soon as the conversation is terminated.

In the embodiment shown in Fig.2, the relay K locks up when operated, so that a recall once having been answered by a second operator, the apparatus will not be returned to the conditions existing after the scriber at Aremoves the receiver 7 from the switch-hook 8, which being spring pressed upward, will close the switch 9, completing a circuit through the magnet of the relay S, as follows: 9the transmitter l07-convductor 11-the switch 12--the magnet of Sthe battery 13-the switch 14the conductor 15back to the switch-hook 8. Current from the battery 13 through this circuit will cause the energization of the magnet ot the relay S, which will attract its armature 16 and close the switch 17, completing a circuit through the line lamps, as follows: from ground l8-through 1317- the conductors 19 and 19' in parallel through the lamps X and a: in parallel and to the grounds 20 and 20, respectively. The lamps are at diiierent positions upon the switchboard, and so located that their illumination is observed by the operators at these various positions. ators will respond to the call. Assuming that it is the operator who controls the cord C, and that cord is to be used, the switching device D is operated by inserting the plug Pinto the jack J, the tip contact 21 and sleeve contact 22 and the ring contactof the plug P registering respectively with the tip spring 24:, the sleeve spring 25 and the ring 4 0f the jack J, and making electrical connection therewith. A circuit will be completed through the relays N and L, as follows: ground 18magnet of N 4-23-c0-nduct0-r 26-switch 27conductor 28-conductor 29-the magnet of the relay L-the resistance device Vthe battery 13, --to ground 18,. The magnets of both N and L will be operated. The magnet N opens the switches 12 and 14;, interrupting the circuit of the magnet S, which releases the switch 17, thereby disconnecting the line lamps X and w from the current source and extinguishing the same, so that no other operator will respond to the call, and the line I will be separated from the line relay and the line lamps. Thence forward during the call, the subscriber will be unable to reoperate any of the line lamps. The magnet L attracts the armature 30, opening a switch 31, for a purpose to be described and closing a switch 32, completing a circuit for One of the operthe magnet L, as previously described, ex-

turing the call, but constitutes no part of my present invention.

The relay L also closes the switches 33, 3st and 35. The closing of the switches 3-1 and 35 completed the circuit of the magnet M and connected the battery 13 to the strands 36 and 37 of the cord circuit. The relay M will now be actuated over the following circuit: ground at 3813 winding 39 of Mconductor 40-35conductor 41switch 42switch 3-t-Winding 45 of M-to ground at 46. The magnet of M opens the switch 47 for a purpose to be de scribed and closes the switch 48, completing a new circuit for the relays L and N, as follows: 18-magnet of N-423263- 4E849-magnet of L32-3O-13 -to ground at 18 The purpose of making this new circuit will be understood from the description which follows.

The magnet of the relay M also closes a switch 50 in the circuit of the relay Q, whose functions will be understood from the description which follows.

WVhen the magnet of L closed the switch 33, a circuit was completed for the magnet of the relay T as follows: 51-magnet of T-conductor 5233conductor 53switch 5lbattery 13 -to ground 55. The magnet of T will be energized by current over this circuit and will close the switches 56 and 57, connecting the operators set to the calling line, so that the operator and the subscriber can converse. The circuit is as follows: from the receiver 58through the switch 56364222-2511-710-9 8-1 5-2421l-3-37-conductor 60-57 back to 58, current being supplied from the battery 13 as previously explained. Over this circuit the operator learns that the subscriber A desires to talk to the subscriber 13. She tests the line III in the well known manner, and assuming that she finds the line idle, operates the switching deviceEby inserting the plug P into the jack J, the circuit connections being made in the same manner as described in connection with the operation of the switching device D. As soon as the device E is operated, a circuit is closed for the magnets of the relays L and N, as follows: ground 55loattery 13 relay Lconductor (SQ-switching device E- magnet of Nground 63. The magnet of N will be operated, disconnecting the line signals and the line relay from the line III in the same manner that the line relay and line signals are disconnected from the line I. The magnet of L will be energized, opening a switch 27 and therefore the branch of the circuit of the relays L and N, which pass through this switch. The relay L also closes a switch at for a purpose to be de cribed, and opens a switch 54 in the circuit of the relay T, which is deenergized,

disconnecting the operators set from the cord; The magnet of this relay clos:s a switch in the circuit of the supervisory lamp 66 and a switch 67 in the circuit of the disconnect lamp W. The lamp 66 will be operated during this period, but the lamp IV will not be operated, because its circuit is open at 31.

The operator then signals the subscriber at B by operating the keys I and I, which are preferably mechanically connected together, so that they are operated together. The operation of I closes the circuit of the ringing relay Q, as follows: ground 68Iconductor 69switch 70- conductor 71now closed switch 50-switch 72 relay Q conductor 73 65 13 to ground 55. The magnet of the relay Q, is

energized, first closing the switch 75 and completing a locking circuit for said relay through the conductor 76 to ground 77, the relay now being energized independently of the contacts of the key at I. The magnet of Q also opens the switches 78 and 79, thereby interrupting the strands of the cord circuit and closes the switches 80 and 81, completing the ringing circuit, which is as follows: ground 82-ringing machine U commutator H-contacts of the key Ithe conductor 83magnet of the relay R-conductor 84:the contacts of the switch 80- through the switch Eover the conductor 85the signal 86the conductor 87back through the switch Ethrough the switch 8lconduc'tor 8Sbattery 89to ground at 90. The commutator H in a well known manner interrupts this ringing, so that the ringing is applied at intervals until the subscriber responds. scriber will change the character of current flowing through the relay R in such a manner that the'salne will be operated, interrupting the circuit of the relay Q, which releases its contacts, restoring them to the condition illustrated in the drawing. The magnet of the relay 1V is then operated over the following circuit: ground at 91winding 92 of the magnet of lWIthe conductor 93through the switch E and over the called line-loack through the switch E through the conductor 94-the winding 95 ground at 97. This magnet opens the switch 72 in the circuit of the relay Q, so that the ringing current will not be accidentally placed upon this line.

The magnet M also opens a switch 99 in the circuit of the signal 66, thereby extinguishing the same. Conversation now takes place between the subscribers at A and B over the limbs of the calling line Ithe contacts of the switching device Dthe strands 36 and 37 of the cordthe contacts of switching device E and the called line III, battery The response of the sub- .115 of the magnet of Mthe battery 96to' being supplied from the source 13 in the manner already described. At the termination of the conversation, the subscribers restore their substation sets to the condition illustrated in the drawing, which as will be appreciated from the previous description, will interrupt the circuits of the magnets M and M, restoring the circuit of the signal 66, which operates, indicating to the operator that the conversation is completed. The deenergization of the magnet of the relay M closes a switch 47 in the circuit of the magnet K, conditioning that magnet for operation by the subsequent action of an operator, which will later be described. Second, the deenergization of the magnet of M opens permanently the circuit of the relay Q at 50 and the circuit of the magets of the relays N and L at as, denergizing the same. The deenergization of L interrupts the circuits of the magnets T and. M and completes the circuit of the disconnect lamp W, as follows: 18 13 81conductor l00-67'Wconductor 101 switch 102to ground 103. The illumination of the lamp W indicates to the operator that the conversation is completed. It frequently happens that the operator does not immediately take down the connections, that is, withdraw the plugs from the jacks to restore the system to normal prepartory to making future connections, and it also frequently happens that during this interval, the subscriber desires a recall, that is, desires an immediate connection. In most systems now in vogue, the magnet of the relay N would continue to be actuated, so that the subscriber at A is still disconnected from his line lamp. As will be seen, however, in my system, the relay N is denergized when the conversation is completed, so that the subscriber can immediately thereafter actuate the line lamps X and w, as previously described.

Assuming that the subscriber at A desires a recall and as soon as the conversation is completed again closes the switch 9, the line lamps will be actuated, as previously described, and assuming that a second operator answers this call by inserting the plug 7) of the cord circuit G into the jack j, the relays N and L will be operated over the follow- 42 and 43, and connecting the commutator G in the circuit of the disconnect lamp W, which will be flashed, giving a special signal to the operator, indicating to her that another operator has answered the recall of the subscriber at A. Should, however, the operator controlling the cord C desire to answer the "ecall of the subscriber at A, the key 0 is operated, closing a circuit through the magnet of the relay L asis deenergized and the operators set F disconnected from the cord, when the relay L is operated, by the opening of ,the circuit of the relay T at 54, in case the key 0 is released.

It will be readily appreciated that when the plugs of the cord C are withdrawn, the apparatus will be returned to the condition illustrated in the drawing, unless the plug of some other cord is in onset the jacks of the line I, when, of course, the apparatus of that cord will be in the conditions described in that particular stage of operation in which it exists at the time such plugs are withdrawn. If the conversation taking place over the connections put up through the cord G, as a result of a recall, is terminated, and the operator controlling the cord C withdraws the plug p from the ack j while the cord C is still connected to 'the line I, the magnets of the vrelays K and N will again be deenergized, restoring their switches to the conditions illustrated in the drawing. This, however, will not take place in the embodiment illustrated in Fig. 2, since in that embodiment the relay K, having been once energized by the insertion of the plug 10, into the jack 7' a locking circuit is completed for the relay K as follows: ground 200-sWitch- 201-conductor 202magnet of Kr-switch 203conductor 204-switch 205 conductor 206-e-b'attery 207to ground 208,]so that the interruption of the strands of the cord 0 prevails after the plug 72 is withdrawn from the jack. Should the operator controlling the cord C answer a subsequent call or recall, this locking circuit of the magnet of the relay K will be broken at 201 and a coil 220 will be placed across the cord circuit. other steps in the operation of the embodiment shown in Fig. 2 will be clear from the description of the operation of the embodiment shown in Fig.

The

I have illustrated these two embodiments of my invention and the details thereof for the purpose of better illustrating and describing my invention. I do not Wish to be limited to such embodiments or details as it will be apparent to those skilled in the art that many departures may be made therefrom without departing from the spirit of the invention.

I claim 1. In a telephone system, the combination of a main station, a plurality of telephone lines leading to the main station, a substation on one of said lines, a plurality of telephone line interconnecting mechanisms at the main station for connecting said telephone line to other lines for conversational purposes, each mechanism including a talking strand and mean jointly controlled by one of said mechanisms and said substation for interrupting the strand of another of said mechanisms.

2. In a telephone system, the combination of a plurality of telephone lines, substations on said lines, a plurality of similar telephone line interconnecting mechanisms for connecting telephone lines together for conversational purposes, each mechanism including a plurality of talking strands and means controlled by each of said mechanisms for interrupting the strands of another of said mechanisms, pre-connected to the same telephone line as said first-named mechanism.

3. In a telephone system, the combination of a telephone line, a substation on said line, a plurality of similar telephone line interconnecting mechanisms for making connection with said telephone line for conversational purposes, each mechanism including a talking strand and an electromagnet controlled by one of said mechanisms for interrupting the talking strands of another preconnected mechanism.

4. In a telephone system, the combination of a telephone line, a substation on said line, interconnecting cord circuits for connecting telephone lines together for conversational purposes, switching apparatus for directly connecting each cord'to a telephone line and means controlled by such switching apparatus of a second connected cord circuit for causing the automatic interruption of the talking strands of another cord circuit when such switching apparatus is operated.

5. In a telephone system, the combination of a plurality of telephone lines, substations on the lines, a main station, a plurality of cord circuits at the main station for connecting telephone lines together, each cord circuit including a plurality of talking strands, switching apparatus for connecting the cord circuits to telephone lines, disconiecting relays for interrupting the talking strands of the cord circuits and means controlled by the witching apparatus at one cord circuit for automatically causing the operation of the disconnect relays of other cord circuits connected to the telephone line to which said last-named cord circuit is connected at the time such connection is made.

6. In a telephone system, the combination of a plurality of telephone lines, substations on said lines, an interconnecting mechanism "for connecting telephone lines together for conversational purposes, said mechanism including a plurality of talking strands, a disconnect relay for interrupting said talking strands, means controlled by a subscriber for conditioning said relay for operation when the subscriber retires, a second telephone line interconnecting mechanism, and means controlled by said second interconnecting mechanism for causing the operation of said disconnect relay when said second mechanism is connected to a telephone line to which the first mechanism is first connected.

7. In a telephone system, the combination of a calling telephone line, a first and second cord circuit, a switch for connecting the first cord circuit to the telephone line, said cord circuit including a talking strand, a disconnect relay for interrupting the talking strand, means controlled by the subscriber on the telephone line for conditioning said disconnect relay for operation when the ubscriber thereon retires and means controlled by said second cord for causing the operation of said disconnect relay when the second cord circuit is subsequently connected to said telephone line.

8. In a telephone system, the combination of a calling line, a cut-off relay for the calling line, .a cord circuit, a switch to connect the cord circuit to the calling line, means controlled by the subscriber on the calling line for causing deenergization of the cut-off relay when a subscriber on the calling line retires, a second cord circuit, means controlled by the second cord circuit for causing the reenergization of the cutoff relay when the second cord circuit is connected to the calling line and a disconnect relay for interrupting the talking strands of the first cord circuit controlled by means of the second cord circuit.

9. In a telephone system, the combination of a main station, telephone lines leading to the main station, telephone line interconnecting mechanism at the main station for connecting telephone lines together, said mechanism including talking strands and means under the joint control of two main station operators whose mechanisms are connected directly to said telephone line and a telephone line subscriber for interrupting the talking strands of the connecting mechanism Without disassociating said mechanism from the telephone lines.

10. In a telephone system, the combination of telephone lines, telephone line interconnecting mechanism for connecting telephone lines together for conversational purposes, said mechanism including talking strands and means under the joint control of two operators whose mechanisms are connected directly to said telephone line and a telephone line subscriber for interrupting the talking strands without disconnecting the mechanism from the telephone lines.

11. In a telephone system, the combination of a main station, a plurality of telephone lines leading to the main station, a cord circuit at the main station including a plurality of talking strands, an operators circuits, switches for connecting thecord circuit (A) to the telephone lines, said cord including talking strands, electromagnets under the joint control of the subscriber and two operators cord circuits for interrupting the talking strands of the cord oilcuit (A), thereby disconnecting the operative parts of the cord circuit from the telephone line.

13. In a telephone system, the combination of a telephone line, a connected cord circuit, a relay for interrupting one or more strands of the cord circuit, means controlled by said subscriber for conditioning said relay for operation when said subscribers substation apparatus is retired, a second subsequently connected cord circuit and means controlled by means of the second cord circuit for causing the operation of said disconnect relay when the second cord circuit isconnected to the telephone line.

14. In a telephone system, the combina tion of a subscribers telephone line, a cord circuit, a disconnect relay for interrupting one or more strands of said cord circuit, means controlled by the subscriber for con-. ditioning said disconnect relay for operation upon the retirement of said subscriber and means separate from the above-mentioned cord circuit controlled by an operator for causing the operation of said disconnect relay.

15. In a telephone system, the combination of a main station, an operators cord YiI'CUll; including a plurality of talking strands, a disconnect relay for interrupting the talking strands of the cord circuit, means controlled by a subscriber on a telephone line for conditioning said relay for operation and mechanism subsequently controlled by a second operator for causing the operation of said disconnect relay.

16. In a telephone system, the combination of a telephone line, operators tele-' phone line interconnecting mechanism including a plurality of talking conductors, a disconnect relay for interrupting said conductors, means controlled by a subscriber on a telephone line for conditioning said relay for operation, a second connected telephone line interconnecting mechanism and means controlled by said second connected mecha nism for causing the operation of said disconnect relay. 7

17. In a telephone system, the combination of a telephone line, an operators telephone line interconnecting mechanism, means for operatively disconnecting said mechanism from said telephone line, apparatus controlled by a subscriber on a telephone line for conditioning said means for operation, a second connected telephone line interconnecting mechanism, and devices controlled by said second connected mechanism for causing the operation of said disconnect means. I

,18. In a telephone system, the combination of a telephone line, a subscriber controlled switch in said line, a cordv circuit for interconnecting telephone lines including a plurality of talking strands, a disconnect relay for interrupting said talking strands, means including said subscriber controlled switch for conditioning said relay for operation, a second cord circuit and mechanism for causing the operation of said disconnect relay when the second cord circuit is connected to the telephone line. i

19. In a telephone system, the combination of-a telephone line, a cut-ofl' relay for said line, a cord circuit, a disconnect relay in said cord circuit adapted to interrupt the talking strands of the cord circuit, a switch for con necting the cord circuit to a telephone line, means for connecting said relays in multiple to a contact of said switch, a second cord circuit and means including a sourceof current for completing a circuit for each of said relays when the second cord circuit is con-j. nected to the telephone line.

20. In a telephone exchange system, subscribers lines, means under control of an operator for interconnecting the lines, similar switching mechanism for connecting said means to a line and apparatus controlled 12 jointly by a subscriber and by an operator independently of said mechanism for severing in; two parts the operators'interconnecting means. i p,

21. In a telephone system, the combination 1 0 of telephone lines, a substation set including a subscribers switch on one of said lines, a

cord circuit for interconnecting said lines, an operators set associated with said cord, devices to connect said set to saidcord, a plug and jack switch for connecting the cord to a line and apparatus independent of said devices controlled jointly by said subscribers switch and another operator than the one for whom said set is provided independently of said plug and jack switch for severing in two parts the operators interconnecting cord.

22. In a telephone system, the combination of a main station, telephone lines leading to the main station, substations on said lines, a plurality of cord circuits at the main station, each cord circuit including one or more talking strands, a relay in a connected cord circuit for interrupting its talking strands, and a circuit for said relay including a portion of its cord circuit without any source of current therein, and a portion of a subsequently connected cord circuit including a source of current.

23. In a telephone system, the combination of a main station, a plurality of telephone lines leading to the main station, substations on said lines, a plurality of cord circuits at the main station for connecting telephone lines together, each cord circuit comprising a plurality of talking strands and a third conductor, a relay for interrupting the talk ing strands of a first-connected cord and a circuit for said relay including portions of the third strand of a plurality of said cord circuits and closed automatically when a plurality of cord circuits are connected to the same line.

24. In a telephone system, the combination of a main station, a plurality of telephone lines leading to the main station, substations on said lines, a plurality of cord circuits at the main station for connecting telephone lines together, each cord circuit comprising a plurality of talking strands and a third conductor, a relay for interrupting the talking strands of a first-connected cord and a circuit for said relay including portions of the third strands of a plurality of said cord circuits, and means under the control of a subscriber governing said circuit.

25. In a telephone system, the combination of a telephone line, a substation on said line, a plurality of telephone line interconnecting mechanisms, one of which is a first-connected mechanism and includes a talking conductor, a relay for interruptin said conductor, a circuit for said relay including portions of a plurality of said mechanisms and means governed by a subscriber on said line controlling said circuit.

26. In a telephone system, the combination of a telephone line, a substation on said line, a plurality of cord circuits, one of which is a first-connected cord circuit, for connecting telephone lines together, switches for connecting the cord circuits to the telephone lines, each cord circuit comprising a plu rality of talking strands, means independent of said switches for interrupting the talking strands of a first connected cord circuit, and a circuit for said means including portions of a plurality 01 said cord circuits.

27. In a telephone system, the combination of a telephone line including line conductors and the contacts of a subscribers receiver hook switch, a cord circuit including talking strands, a plug and jack switch for connecting the cord to the telephone line, a relay having contacts in the cord circuit, said relay adapted when actuated to interrupt the talking strands of the cord circuit, thereby severing the cord and leaving the plug in the jack, a circuit for said relay, a second relay controlling the circuit of the first relay, a circuit for the second relay including the line conductors and contacts of the switch hook, a disconnect signal, a circuit for said signal and a commutator and means controlled by said first-named relay to connect the commutator in the circuit of the disconnect lamp.

28. In a telephone system, the combination of a. subscribefis telephone line, an operators telephone line interconnecting means, a switch for connecting said line and means together, apparatus under the joint control of a subscriber and two operators for disconnecting said means from said line for operative purposes, without disturbing said switch.

29. In a telephone system, the combination of a subscribers telephone line, asubscribers telephone on said line, a line signal associated with said line at a main station, subscriber controlled means to operate said line signal, operators connecting means to connect sald telephone line to other telephone lines, said connecting means having talking strands and a relay, said relay being adapted when operated to interrupt said strands, means controlled by the main station operator in the act of making connection with the telephone line to remove the control of the line signal from the subscriber and means under the control of the sul scriber to restore the control of the line signal to the subscriber, and means to operate said relay to interrupt said talking strands, said means including a switch in the circuit of a second operators connecting means.

30. In a telephone system, a telephone line, substation apparatus on said line, a line sig nal associated with said line, manually 0perated connecting means to connect said telephone line with other telephone lines, said manually operated connecting means adapted when operated to remove the control of the line signal from the substation apparatus, electromagnetic means under the control of the subscriber for restoring said conpreviously connected, and means including a circuit including a portion of said second named connecting means to disconnect the talking strands of said first named operators connecting means. o

31. In a telephone system, the combination of a subscribers telephone line, an operators telephone line interconnecting means, a switching terminal associated with said line, a second switching terminal associated with said interconnecting means, means associated with said interconnecting means for placing a busy potential upon said first, named switching terminal, subscribers controlling apparatus for removing said busy potential from said switching terminal, means for severing the talking strands of said interconnecting means, said means including a circuit which includes in part a portion of a second interconnectin means subsequently associated with the telephone line. v

32. In a telephone system, a cord circuit, a line circuit and a second cord circuit, a switch to connect said first named cord cirsuit to said line circuit, a substation connected to said line circuit, electromagnetic apparatus in said cord circuitunder the control of said sub-station apparatus, a disconnect signal controlled by said substation apparatus and associated with said first named cord circuit, and a switch to subsequently associate the said second named cord circuit w1th sald telephone line, and means associated with sald first named cord clrcuit to alter the character of the disconnect signal when said last named switch is operated.

33. In a telephone system, the combination of a telephone line, including subscribers substation apparatus, line signal apparatus associated with said line and normally under the control of the'subscriber, telephone line interconnecting mechanism and a switch for connecting said mechanism to said line, means actuated when said switch is closed to remove the control of said line signal ap--- Copies of this patent may be obtained for five centseach, by addressing the Commissioner of Patents, Washington, D. G. 

